1. Technical Field
The present disclosure generally relates to surgical fastener appliers, and more particularly, is directed to surgical fastener appliers of the type which are used for closing wounds in skin and fascia tissue.
2. Background of the Related Art
The placement of clips and staples by surgical fastener appliers for closing wounds in skin and fascia tissue is well known. By way of example, U.S. Pat. No. 4,410,125 to Noiles et al. discloses a surgical stapler apparatus with a staple pusher plate for forming staples around tissue. The staples are fed successively into instrument jaws and cammed closed around skin or fascia tissue by the pusher plate. The staples are stored in the instrument in a longitudinal stack which is substantially parallel to the longitudinal axis of the instrument. The distal-most staple in the stack is applied to the tissue by being bent or formed around an anvil tip of an anvil plate. An actuator adjacent the proximal end of the pusher plate reciprocates the pusher plate along its trajectory so that the distal end of the pusher plate advances the distal-most staple to the anvil and forms the staple around the anvil.
Furthermore, the Noiles et al. surgical stapler includes a metal staple track for carrying the stack of staples. The metal staple track is covered along an outer portion thereof with a plastic bottom or lower housing cover which forms an exterior portion of the surgical stapler. The staples are maintained at an inclined position relative to the metal staple track with staple tips in sliding contact with the metal track. As the pusher plate is cammed toward the anvil, the distal end portion of the pusher plate slides against and beyond a distal end portion of the metal track forming a nose gap space between an underside of the anvil plate and the distal end portion of the metal track. The nose gap space keeps the pusher plate free from galling or binding with the metal track as repeated staples are fired from the stapler.
While the Noiles et al. surgical stapler is an excellent design, the staple cartridge includes a lower portion having two separate parts, namely, the metal staple track and lower housing which increases the cost of manufacture. Additionally, the Noiles et al. surgical stapler is designed such that the staples are maintained at an angle relative to the longitudinal base of the metal track with staple tips in contact with the metal track as the staples are presented for firing. Thus, the metal track serves as a buffer and guide for movement of the staples along the firing track. Finally, a nose gap space exists in order to prevent the pusher plate from galling or binding with the metal track as the pusher plate slides between the underside of the anvil plate and the end portions of the metal track.
Accordingly, a need exists in the art for a new and improved surgical stapler which effectively fires clips/staples into skin or fascia tissue which is formed with fewer parts, provides smooth operation and results in lower manufacture cost.
Therefore, the embodiments herein disclosed throughout the present disclosure achieve the intended purposes, objects, and advantages through a new, useful and unobvious combination of component elements, with the use of a minimum number of functioning parts, at a reasonable cost to manufacture, and by employing readily available materials.
With particular reference to FIGS. 1 and 2, there is illustrated a perspective view (FIG. 1) of a prior art surgical stapler 60, namely, the Royal Auto Suture (.TM.), available from United States Surgical Corporation of Norwalk, Connecticut and an exploded view (FIG. 2) of a prior art cartridge assembly 10 for use in a portion of the surgical stapler 60. Surgical stapler 60 is made up of central body part 62, top cover 64, lower housing 40 and proxinally extending portion 68. Proximally extending portion 68 is sized and shaped to fit comfortably in the palm of an operator's hand, with trigger handle 70 being within the reach of one or more fingers of that hand. Trigger handle 70 is pivotally mounted on the central body part 62 by way of pivotal axis 72 which includes projections 48 extending from lower housing 40.
As best illustrated in FIG. 2, the cartridge assembly 10 contains a plurality of staples 74 formed in a stack along a bottom portion thereof. The cartridge assembly 10 includes an upper chassis assembly 12 which includes cartridge housing 14. Cartridge housing 14 is coupled to central body part 62 of surgical stapler 60 via projections 50. Cartridge housing 14 includes a central channel 16 for receiving pusher follower 18 and compression coil 20. Pusher follower 18 is biased distally by compression coil 20 and includes securing projection 19 for securing reciprocally advancing pusher plate 22. Both the pusher follower 18 and pusher plate 22 move distally against the bias of compression coil 20 within central channel 16. Pusher plate 22 includes staple forming projections 58 which, when distally advanced around a periphery of anvil tip 28 (to be described later herein), form staple 74 into tissue. Cartridge housing 14 further includes a proximally located tab projection 52 which is coupled to an underside of central body part 62. Tab projection 52 acts as a backstop for a proximal portion of a compression spring (not shown).
Along a top portion of upper chassis assembly 12 is positioned an anvil plate 26 which is affixed onto projections 24 of cartridge housing 14. Anvil plate 26 includes anvil tip 28 which is used to form staples 74 as pusher plate 22 is distally advanced against an underside of anvil tip 28. Anvil plate 26 further includes anvil plate projections 35 and grooves 34. Pusher plate 22 forms an arc of a circle as it is distally advanced along the underside of anvil plate 26 toward anvil tip 28. A wrap portion 30 is snap fit over anvil plate 26 and includes projections 32 which fit into the grooves 34 between anvil plate projections 35. The projections 32 are used to bias staples 74 into a staple forming position as each staple 74 is formed around anvil tip 28 and corresponding tissue.
The cartridge assembly 10 further includes a lower chassis assembly 36 having a metal staple track 38 and lower housing 40. Lower chassis assembly 36 is coupled to an underside of upper chassis assembly 12 and secures the plurality of staples 74 therebetween. Metal staple track 38 is fitted between cartridge housing 14 and lower housing 40 and includes channels 42 and flat portions 46 for longitudinally storing a stack of staples 74. Metal staple track 38 further includes a longitudinally spaced central depression 43 over which is received staple follower 45 and associated compression spring (not shown). The ends of staples 74 slide along the flat portions 46 of metal staple track 38 as staple follower 45 and associated compression spring distally bias the stack of staples 74 toward anvil tip 28. Lower housing 40 includes proximally located projections 48 to which trigger handle 70 is pivotally mounted. Along proximal portions of metal staple track 38 and lower housing 40 include cut out window portions 54 and 56, respectively. The window portions 54 and 56 provide an open space along the distal end portion of the underside of the lower chassis assembly 36 and allow ample space for the proper formation of the staples 74 around the tissue.
In the formation of staple 74 around tissue, pusher plate 22 and staple forming projections 58 are advanced distally of anvil tip 28 and distal end portions 49 of metal staple track 38. Such advancement of pusher plate 22 between anvil plate 26 and distal end portions 49 of metal staple track 38 causes frictional contact between pusher plate 22, anvil plate 26 and metal staple track 38. To this effect, there exists a nose gap space between an underside of the projections 35 of anvil plate 26 and the distal end portions 49 of metal staple track 38. This nose gap space keeps the pusher plate 22 free from galling or binding with metal staple track 38 as repeated staples are fired from the surgical stapler 60.
The stack of staples 74 contained within the lower chassis 36 and along the metal staple track 38 are maintained at an incline relative to the metal staple track 38. The inclined positioning of staples 74 serves to properly align the staples 74 for firing. The inclined position of the staples 74 is generally equal to the inclination of pusher plate 22 as pusher plate 22 slides under anvil plate 26 and around the periphery of anvil tip 28. With the staples 74 in this inclined position relative to the metal staple track 38, the staple tips are in sliding contact with metal staple track 38 as they are distally advanced toward the firing position.